2,4,6-Trichlorobenzoic Acid: Structure and Hydrogen-Bonding Pattern

This is an uncommon structure with Z = 12 in space group P2₁/n. The three molecules of C₇H₃Cl₃O₂ in the asymmetric unit consist of one complete carboxylic acid dimer at a general position and one-half of a second unique dimer located at a crystallographic inversion center. Each of the three acid molecules in the asymmetric unit displays carboxyl bond lengths and angles that are nearly equivalent to each other (as opposed to the highly defined C=O and C-O distances, and C-C-O angles that occur in very ordered dimeric systems).

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